Abstract

The project objective is to determine the effects that the killing of
coyotes by farmers and ranchers have on the coyote's ecological system.
To accomplish this, an object oriented C++ program will be designed to
calculate the food consumptions of coyotes, their prey, and other animals
that are involved in the coyotes' ecosystem. This will require a function
for each component of the bionetwork. The main function will represent
the coyote's ecosystem as a whole. This project should determine to what
extent the coyote population could be reduced, before there are major
effects upon ecological system of the given area.

Research

Coyotes (Canis latrans) are members of the canine family. They are about
1.5 to 2 feet tall, range from 41 to 53 inches long, and weigh from 20 to
50 lbs. (Burt, 69). Though they look similar to dogs, their tails are more
bushy and their noses more elongated (wassink,52).

Coyotes are very successful breeders as can be seen by their population in
New Mexico. Although only 5%-20% of pups survive their first year the
coyote population is still very large (…dy_cycot.html). This success is
partly due to the fact that coyotes, when a mate cannot be found, will
sometimes mate with domestic dogs, or other species such as grey wolves
(…~swopejack…). Both males and females are able to breed from about 9-10
months old and do so typically once a year. In a pack, usually only one
pair of coyotes breeds each year (the alpha male and female) (Bekoff 3).
Some evidence has been found that coyote pairs mate for life (Jan 52). The
females oestrous cycle lasts about 2-5 days and ovulation occurs 2-3 days
before the end of female receptivity. The gestation period is usually
about 63 days and litters usually contain 6 pups (Bekoff 3). During the
time that the pups are helpless the female guards the den and protects the
pups, while the male brings food to the female (bok 32). When the pups
are ready to eat semi-solid food the mother chew up pieces of meat that
she feeds to the pups. The pups emerge from the den at about 2-3 weeks of
age, and are weaned about 2 weeks later (Green, Henderson, Collinge, 53).
The pups then leave their mother at about 9 months, some however stay till
a year old (Bekoff 4). When they leave the den they will look for places
with abundant food and mates.

One of the reasons coyotes adapt so well is their feeding habits. Coyotes
are omnivores; they will we feed on any food source that is abundant.
Though their main diet consists of rabbits, squirrels, and other small
rodents, they will frequently feed on carrion, and when they hunt as packs
they have been known to kill larger animals such as elk, or deer
(…du_cycot.html). Coyotes are the leading killers of elk in the
Yellowstone National Forest. They kill about 1350 elk per year. If no
other food source can be found they will also feed on berries, other
plants, and even trash (Green, Henderson, Collinge, 52). Coyotes are like
other predators; they are very opportunistic. They will usually take down
the prey that is easiest to catch. This means that they will usually kill
young or sick animals, but in some cases, they will take the stronger
animals, even though young or weak are present. They do this because the
strong animals are usually on the edge of the group, and are therefore
easier to catch (Green, Henderson, Collinge, 52). Coyotes occupy territory
all the way from Alaska across to Vermont and through Mexico (Burt, 69).

They can live in mountainous areas, plains, and even sometimes in cities.
There have even been documented cases of coyote pairs living in large
cities such as Los Angeles, living off the trash they find. Part of this
may be the fact that coyotes will eat any abundant food source, even food
scraps from trash (Green, Henderson, Collinge, 52). However, they usually
prefer to live in the edges of fields near forests. Their territories
range from 300 acres to 100 square miles. Another part is the supreme
adaptability of coyotes to their surroundings, without drastically
changing their behaviors or physical traits, such as growing white fur in
snowy regions or very much longer fur in the northern regions.

Coyotes have flourished all over North America, even in the face of
adversity. They have been maligned, given a bad reputation, and many
attempts have been made to exterminate them, but they still prosper, and
spread. Coyotes have been compared to humans in their adaptability, and
the sheer land area they occupy shows this. And though they are
considered to be pests by many people, without their eating of carcasses,
livestock diseases would be rampant.

A coyote's design is superior to most other animals. They are optimized
for hunting, with very good senses of hearing and smell, and amazing speed
(coyotes can run up to 40 mph)(Green Henderson, Collinge, 53). This is
what makes them so dangerous when hunting in packs, or even alone.

Their pack behaviors are similar to that of other wild dogs. They have a
social hierarchy with an alpha male, who dictates the some of the
behaviors and hunting rituals of the pack. The alpha male usually rises
to that rank in the way most alphas or dominant animals do, by fighting
and beating the previous dominant alpha male.

Coyotes' hunting habits are also similar to that of their wolf, and wild
dog cousins. When alone, or in pairs, they will usually hunt for small
animals like squirrels and rabbits. When they are in a large pack,
however, they have been known to take down larger animals such as elk and
deer. Although they prefer to kill adolescent split hoofed mammals, they
will, when hunting as a pack, kill the adult animals (Green, Henderson,
Collinge, 52).

In the plains states, or regions where livestock is raised, they have been
known to kill sheep and other livestock (knowlton,1114). This is one of
the main reasons they have been exploited, and in some places driven
almost to endangerment. Many ranchers have fought to have the coyotes
eradicated because of the endangerment to their livestock. But his has
been prevented by the work of environmentalists who realize that the
coyotes are an integral part of their regional ecosystems.

Many different methods are used to attempt to keep coyotes away from
livestock. One of the most common types is, of course, fencing, but this
has many times proven near useless. Although fences will stop some
coyotes, the older and more experienced one will usually find a way past
them. Coyotes will usually either climb over the fence or dig under it
(Green, Henderson, Collinge, 55). Many new fence designs, including
electric fences have increased the protection abilities of fences. Many
now use a barbed wire overhang to prevent scaling, and a buried apron of
wire to prevent digging under (Green Henderson, Collinge, 55).

A rather odd but seemingly effective way of deterring coyotes in use in
Texas is donkeys. Donkeys have an extreme dislike towards intruding dogs,
which causes them to attempt to kill the intruder. The donkeys will bray,
kick, bite, and charge at the animal until it is either dead or gone
(Green, Henderson, Collinge, 61). Although there has been only a small
amount of research done on the use of donkeys as guards, they have become
fairly popular with ranchers in Texas (Green, Henderson, Collinge, 61).

One kind of device that is useful for short periods of time, are
frightening devices, that include, lights, loud noises, etc. They are
only useful for short periods, because eventually the coyotes will
acclimatize to them and ignore them (Green, Henderson, Collinge, 59).
One of the most popular types of deterrence (because of their relative
cost effectiveness) are guard dogs. These dogs are trained from
adolescence not to harm the sheep, and to drive away intruders. This is
accomplished by having the pups associate with sheep from a very early
age, which forms a bond between sheep and dog. The dogs will then
instinctively protect the sheep (Green, Henderson, Collinge, 61).

One of the oldest and most widely used deterrents is trapping. This uses
steel traps (much like ones used to trap bears), and things that would
attract a coyote to them. When setting a trap farmers usually partially
cover the trap with dirt, and place coyote urine or droppings near the
trap. When the coyote finds the scent it will walk towards it, and
hopefully step in the trap (Green, Henderson, Collinge 64).

Computational Plan

The purpose of this program is to determine the effects of the coyote
population on the ecosystem. The program will produce outputs of
information about the coyote population, and the population of their prey.
The program will be a model based on the Cuba area forest and surrounding
land. The initial amount of coyotes will be based on the present
estimated population of coyotes supplied by the forest service. Then, the
population of rabbits, mice rats, gophers, squirrels, insects, birds, and
deer will be included as elements of the food supply. The program will
also include weather conditions. This program will utilize elements of
random selection to establish the growth rate of the coyote population.

However, to complete our project, we must obtain the current coyote
population, and the population of their prey. We must also determine the
amount of meat that coyotes consume in a certain amount of time, and the
percentages of each animal that they eat. We have encountered obstacles
in obtaining this critical information. However, we are making progress.

Program inputs:

Command to retrieve week by week data of coyote and rodent population,
weather conditions, and the amount of coyotes killed by disease and
ranchers.

Program outputs:

Coyote population

Rabbit population

Weather

Rodent population

Coyotes killed by ranchers

Disease coyotes

Formulas:

X(n)=X(n-p)*X(n-q) Mod M

r n=ar n-1 (Modulo m)

These formulas will generate random numbers to determine weather patterns,
disease, and mating among coyotes and it's prey.

Progress to Date

Our group has been successful in finding important research on coyotes.
We have found important information that indicates the average amount of
coyotes per liter, the survival rate of the pups, and the frequency of
coyote births. We have also obtained information about the components of
coyote's diet, which indicates their prey. The size of coyote territories
has also been determined, which is important in determining the amount of
land that they require. Another important aspect of our project that we
have researched is the methods that ranchers use to keep coyotes from
killing livestock.

Results Expected

Our program will be expected to output data that indicates the coyote
population, the population of their prey, the weather conditions, and the
amount of coyotes that were killed by ranchers. This program will keep a
count of coyote population and all of its prey. The count will increase
or decrease with the changing weather conditions generated by the random
number generator. We will then complete a statistical analysis of this
data based on statistical values that have already been established.

Bibliography

Bekoff, Marc, Coyotes: Victims of Their Own Success. (Online)Available
http://users.ox.ac.uk/~wcruinfo/esgweb/publicat/endnews3/coyotes.html,
November 29, 1999.

Burt, William H. A Field Guide to the Mammals. Boston: Houghton Muffin
Company, 1976.